Sorry but I can't help myself. Seems that a certain poster(s) on SH are questioning the very process used by SGS.

Metallurigical Balancing

Metallurgical balances are fundamental to the successful design and operation of concentration and dewatering circuits. With computerized balance techniques gaining prominence in recent years, it is essential that engineers understand the basic principles that underlie the new methods, as well as the various applications for design of new plants and analysis of existing operations.

http://www.onemine.org/search/summary.cfm/Metallurgical-Balances?d=93BA26402A68C8596457EE4311181B845BD7F94DC3A722D54546703928ABF3052432

Ash Analysis

http://www.sgs.com/en/Trade/Commodity-Trading/Ore-Coal-Biofuels-Steel-and-Fertilizers/Coal-Coke-and-Biofuels-Analysis/Ash-Analysis.aspx

Perhaps others have better links to share.